The need for light weight ablative materials for aerospace and military applications is well established. An extensive report identified as AFWAL-TR-81-4171, Part II, by D. D. Woolley dated December 1982 entitled DEVELOPMENT OF CARBON-CARBON COMPOSITES WITH IMPROVED CHARRING CHARACTERISTICS describes composite structures and the advantages of these materials. U.S. Pat. No. 4,284,834 gives a good outline of this need and proposes that homopolymerizable diethynyl substituted aromatics be used for this purpose. U.S. Pat. No. 4,374,291 discloses a process of producing a class of such materials defined as bis(ethynylphenyl) compounds which comprises diazotizing particular diphenyl dianalines to form a dihalogenated diphenyl compound, coupling it with ethynyltrimethylsilane in the presence of an organopalladium complex and a ligand to yield an end-protected diphenyl compound having acetylenic moities thereon, and subsequently removing said end-protecting groups from the diphenyl compound by treating the end-protected compound with a weak base in an inert atmosphere. This process is characterized by low yield and the product, while suitable for the intended purpose, is very expensive.
Processes for preparing certain ethynyl aromatic compounds involving a halogenation operation have been proposed, but such processes are applicable only to starting materials which have no reactive aliphatic hydrogen atoms. Compounds having such reactive hydrocarbons when used in prior art processes give undesirable side products. See, for example, the article by Sabourin et al. entitled A CONVENIENT SYNTHESIS OF 4-ETHYNYLPHTHALIC ANHYDRIDE VIA 2-METHYL-3-BUTYN-2-OL, J. Org. Chem. 48, pp 5135 et seq., 1983.